Timing device



March 8, 1955 w. o. HANCOCK TIMING DEVICE Filed Aug. 3, 1953 INVEN TOR. M41 1AM Q fiffi/vc cfi BY United States Patent TIMING DEVICE William 0. Hancock, Knoxville, Iowa Application August 3, 1953, Serial No. 371,915 3 Claims. (Cl.123139) This invention relates in general to timing means and in particular, to a device for adjusting the time of injection into a diesel engine so that it can operate efiiciently over a wide speed range.

Diesel engines have been known for some time and have proved themselves to be very reliable. They have always been designed for a particular speed and do not operate very well when this speed is not used. Thus, when diesels are used in trucks large gear boxes are installed to allow the operator to maintain a constant engine speed. When the speed of the vehicle is varied, the operator shifts gearsto obtain a different gear ratio. The best speed of a diesel depends to some extent on the time of injection of the fuel and the injection is conventionally fixed. Thus, injection might occur just before the piston reaches dead center. This injection is most eflicient for the designed best operating speed but is too early or too late at other speeds. For example, at slower speeds the injection should be made later and at faster speeds it should be made earlier.

Therefore, it is a main object of this invention to provide an automatic timing device for a diesel type engine.

Yet another object of this device is to provide an efficient variable speed diesel engine.

A further object is to provide a timing mechanism which is controlled by the engine itself so that it automatically adjusts the time of injection.

A feature of this invention is found in the provision for a mechanism between the drive shaft and pump shaft of a diesel engine which adjusts their phase angle according to the load on the pump shaft.

Further features, advantages and objects will be apparent from the following description and claims when read in view of the drawings, in which:

Figure 1 illustrates the timing device of this invention mounted on a diesel engine;

Figure 2 is an end view of the engine; and

Figure 3 is a detail view of the timing device according to this invention.

Figure 1 illustrates a diesel engine which has a drive shaft 11 rotatably mounted therein. A crank arm 12 is integrally formed with the drive shaft 11 and a connecting rod 13 is connected thereto in a conventional manner.

A piston 14 is connected to the connecting rod 13 and is received in a cylinder 16 of the engine. Suitable valves 17 are provided in a conventional manner. The engine illustrated has four cylinders but it is to be realized that the invention is applicable to any number of cylinders.

A supporting bracket 20 supports one end of drive shaft 11 and a drive gear 18 is attached thereto. The bracket 20 also rotatably supports a cam shaft 19 which carries a gear 21 that is in mesh with gear 18. Gear 21 has twice the number of teeth as gear 18.

Gear 21 meshes with one half of a timing gear 22 which is supported on shaft 23 that is rotatably supported between the engine and bracket 20.

A pump shaft 24 is supported by the engine 10 and the bracket 20 and carries a pump gear 26 which meshes with the second half of timing gear 22. Four injection pumps 27, 28, 29 and 30 are driven by pump shaft 24. These pumps supply the fuel which is injected into the cylinders of the engine and have a fixed time relation so that the injection will always occur at fixed angular positions of shaft 24.

Figure 3 illustrates the timing gear 22 in greater detail. It is to be noted that shaft 23 is mounted in sleeves 31 and 32 connected respectively to the engine 10 and the bracket 20. The shaft may move longitudinally in sleeves 31 and 32.

A biasing spring 33 is mounted within sleeve 32 and engages the end of shaft 23. A disc 34 compresses spring 33 and is attached to a threaded shaft 36 which is thread- 2,703,563 Patented Mar. 8, 1955 edly received through a threaded collar of sleeve 32. A thumb screw 38 is attached to the free end of shaft 36.

As shown, the timing gear 22 is formed in two parts 39 and 41. Each part is substantially wider than gears 21 and 26 which mate therewith. Gears 21 and 26 have teeth that are cut at an angle. Likewise, the parts 39 and 41 have teeth that are cut at an angle so as to mesh with gears 21 and 26.

In operation, the shaft 23 moves longitudinally in response to speed variations of the engine. This is true because as the engine speed changes, the torque required to drive the pumps 27, 28, 29 and 30 changes. This causes the torque transmitted from gear 21 to gear 26 to change. Due to the fact that the teeth of gears 21, 26 and 22 are cut at an angle a longitudinal component of force will be developed which will move shaft 23 longitudinally. Since this component of force varies with the applied torque the shaft will assume a position of equilibrium for the particular applied torque.

Adjustment of thumb screw 38 allows the torque versus movement characteristic to becontrolled.

As. the shaft 23 moves longitudinally the phase angle between shafts 19 and 24 changes because of the angle of teeth of the gears. Thus, the time of injection from the pumps will change with movement of shaft 23. Since shaft 23 moves longitudinally with speed changes the time of injection will also vary with speed changes.

The posterior or later injection corresponds to the position of gear 22 shown in Figure 3 and the advanced injection position is shown in Figure 1.

Figure 2 shows the gears and shafts from the end.

Thus, it is seen that this invention provides means for continually varying the time of injection in a diesel engine so that it may operate more efiiciently over a wide speed range.

Although this invention has been described with respect to a preferred embodiment it is not to be so limited as changes and modifications may be made which are within the full intended scope as defined by the appended claims.

I claim:

1. A timing device for a diesel engine comprising, a timing shaft rotatably supported by said engine and free to move longitudinally, a spring mounted between said engine and the timing shaft to bias it in one direction, a timing gear mounted on said timing shaft and formed with two parts, each of said parts formed with teeth out at different angles, a cam shaft supported by said engine, a cam gear with teeth out at an angle mounted on said cam shaft and engageable with one part of the timing gear, and a pump gear mounted on a pump shaft and formed with teeth out at an angle and engageable with the second part of the timing gear.

2. A timing device for a diesel engine having a cam ice shaft and a pump shaft comprising, a cam gear cut with teeth at an angle mounted on the cam shaft, a pump gear cut with teeth at an angle mounted on the pump shaft, a timing shaft rotatably mounted on the engine and free to move longitudinally relative thereto, a biasing spring attached to the engine and the timing shaft to bias it in one direction, a timing gear mounted on the timing shaft and formed with two parts, the two parts of the timing gear formed with teeth which are cut at different angles, the cam gear engageable with one part of the timing gear, and the pump gear engageable with the other part of the timing gear.

3. A timing device for a diesel engine having a cam shaft and a pump shaft comprising, a cam gear cut with teeth at an angle mounted on the cam shaft, a pump gear -.cut with teeth at an angle mounted on the pump shaft,

a timing shaft rotatably supported by the engine and free to move longitudinally relative thereto, a biasing spring attached to the engine and in engagement with the timing shaft to bias it in one direction, means for adjusting said spring, a timing gear mounted on the timing shaft and formed with two parts, the two parts of the timing gear formed with teeth which are cut at different angles, the cam gear engageable with the first part of the timing gear, and the pump gear engageable with the second part of the timing gear.

No references cited. 

